Polyprotic Acid Titration Calculator

Advanced Titration Analysis

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Multiple Equivalence Points Calculator

Calculate pH at multiple equivalence points for polyprotic acids.

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Multiple Buffer Regions Calculator

Calculate buffer regions and capacities for polyprotic systems.

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Species Distribution Calculator

Calculate distribution of species at any pH.

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Understanding Polyprotic Acid Titrations

Basic Principles

Key concepts include:

  • Multiple dissociation steps
  • Successive equilibria
  • Buffer regions
  • Species distribution
  • pH curves

Titration Curves

Important features:

  • Multiple Points:
    • Equivalence points
    • Half-equivalence points
  • Buffer Regions:
    • Multiple buffers
    • Overlapping effects

Applications

Common uses:

  • Phosphoric acid analysis
  • Amino acid titrations
  • Environmental analysis
  • Biochemical systems
  • Water treatment

Advanced Concepts

Additional topics:

  • Microscopic equilibria
  • Tautomerization
  • Ionic strength effects
  • Temperature dependence
  • Activity coefficients

Essential Polyprotic Acid Formulas

Dissociation Constants

Ka₁ = [H⁺][HA⁻]/[H₂A]

Ka₂ = [H⁺][A²⁻]/[HA⁻]

Ka₃ = [H⁺][A³⁻]/[A²⁻]

Species Distribution

α₀ = [H⁺]²/D

α₁ = Ka₁[H⁺]/D

α₂ = Ka₁Ka₂/D

D = [H⁺]² + Ka₁[H⁺] + Ka₁Ka₂

Buffer Capacity

β = 2.303([H⁺] + ΣKaᵢ[H⁺]ⁱ⁻¹/D)

Where:

D = Denominator term

i = Number of dissociations